PCV valve
02-02-2018, 03:26 PM
#1
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Thread Starter
PCV valve
Hello everyone, I am new to this web site and its forums, I have a 2006 F150 STX with a 4.6. I changed the PCV valve because it was rattling, after I installed the new one the truck runs so slow it actually stalls, I install the old one back in and it runs great just sounds like a rattlesnake under the hood I think the new PCV is defective. This may be a stupid question but are there different types of PCV valves for air flow, kind of like different temperatures for thermostats. Just curious if anyone has had something similar happen to them.
Thank you
Thank you
02-02-2018, 03:33 PM
#2
PCV valves are best described as a calibrated vacuum leak and yes they are engine specific. You might have a good one but it may not be right for your application.
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Powerbiz (02-02-2018)
02-02-2018, 05:44 PM
#3
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The PCV valve is supposed to rattle (when shaken), but it's not supposed to be audible on the running engine. But it's not a bad valve that causes the rattle, so changing the valve won't fix the problem.
The quickest way to find the problem might be a smoke test (which requires expensive equipment) or a compression test. But you could probably make some headway with a mechanic's stethoscope or 3' of garden hose. Click these & read the captions:
(phone app link) (Ignore that diagram - just read the caption.)
(phone app link)
(phone app link)
The quickest way to find the problem might be a smoke test (which requires expensive equipment) or a compression test. But you could probably make some headway with a mechanic's stethoscope or 3' of garden hose. Click these & read the captions:
(phone app link) (Ignore that diagram - just read the caption.)
(phone app link)
(phone app link)
02-02-2018, 06:13 PM
#4
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02-02-2018, 06:29 PM
#5
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Yes, I've heard them in my decades repairing vehicles. But it's like a buzz in the radio - you don't change out the radio to fix it. You find the actual root cause of the buzz, and fix THAT. The worst-worn PCV valve in the world won't buzz in an engine that runs right; there should be nothing creating a high-frequency pulse of air in the PCV hose to make the valve buzz.
Sure, a new radio with better RFI shielding, or a new PCV valve might suppress the buzz - but you didn't actually fix the problem. You just hid it.
Sure, a new radio with better RFI shielding, or a new PCV valve might suppress the buzz - but you didn't actually fix the problem. You just hid it.
02-02-2018, 06:33 PM
#6
Yes, I've heard them in my decades repairing vehicles. But it's like a buzz in the radio - you don't change out the radio to fix it. You find the actual root cause of the buzz, and fix THAT. The worst-worn PCV valve in the world won't buzz in an engine that runs right; there should be nothing creating a high-frequency pulse of air in the PCV hose to make the valve buzz.
Sure, a new radio with better RFI shielding, or a new PCV valve might suppress the buzz - but you didn't actually fix the problem. You just hid it.
Sure, a new radio with better RFI shielding, or a new PCV valve might suppress the buzz - but you didn't actually fix the problem. You just hid it.
Welcome to my ignore list.
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Last edited by RLXXI; 02-02-2018 at 06:36 PM.
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techrep (02-03-2018)
02-03-2018, 01:03 PM
#7
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Boy, I'm glad he's not going to reply to what he's misreading any more! 
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02-03-2018, 02:40 PM
#8
Mark
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The OP says his is rattling and the new one don’t.. so obviously the valve is bad, now on to finding the correct replacement. OP... get the part number off the old valve and bounce it against the new one to ensure correct valve. Like stated above.. new one should rattle when shaking by hand.
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RLXXI (02-03-2018)
02-09-2018, 07:00 AM
#9
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Ok, I just don't get it, I know I am not a certified mechanic but I have always done most of my own work, from changing my manifold, lifters, carb, ball joints etc in my old chevy, for the life of me I can not figure this out. I bought two different PCV valves for my 2006 F150' like I said in the early post the old one rattles when the truck is running. When I put the new ones in the rattle is gone but the truck runs at a low RPM and will stall if I do not keep the RPM up enough, put the old one back runs fine just has a rattle..... I just don't get it... Could it be possible that its in the computer and the settings need to be modified?
